6,6′-Diamino-1,1′,3,3′-tetra­methyl-5,5′-(4-chloro­benzyl­idene)bis­[pyrimidine-2,4(1H,3H)-dione]

The title compound, C19H21ClN6O4, is a 1:2 adduct of p-chloro­benzaldehyde and uracil. It crystallizes with two mol­ecules in the asymmetric unit. The two uracil units in the same mol­ecule are connected by a pair of strong N—H⋯O hydrogen bonds. The packing is stabilized by N—H⋯O, C—H⋯O and C—H⋯N inter­actions

6-[(Dimethyl­amino)methyl­ene­amino]-1,3-dimethyl­pyrimidine-2,4(1H,3H)-dione dihydrate

Uracil, the pyrimidine nucleobase, which combined with adenine forms one of the major motifs present in the biopolymer RNA, is also involved in the self-assembly of RNA. In the title compound, C9H14N4O2·2H2O, the asymmetric unit contains one dimethyl­amino­uracil group and two water mol­ecules. The plane of the N=C—NMe2 side chain is inclined at 27.6 (5)° to the plane of the uracil ring. Both water mol­ecules form O—H⋯O hydrogen bonds with the carbonyl O atoms of the uracil group. Additional water–water hydrogen-bond inter­actions are also observed in the crystal structure. The O—H⋯O hydrogen bonds lead to the formation of a two-dimensional hydrogen-bonded network cage consisting of two dimethyl­amino­uracil groups and six water mol­ecules

Formation of carbon quantum dots and graphene nanosheets from different abundant carbonaceous materials

Carbon quantum dots (CQDs) and graphene nanosheets (GNs) are one of the most attractive fluorescent carbon nano-sized materials with unique features of optical and physico-chemical properties having various applications in chemical sensing, biomedicine, semiconductor devices, photo-catalyzing, and electrocatalysis. The primary purpose of this preliminary work is the feasibility study for synthesis of nano-structured value-added carbon products i.e., CQDs and GNs from cheap and abundant carbon sources, such as coal, petroleum coke, graphite, and coal-based humic acid by hydrothermal techniques. The physico-chemical properties of the raw precursors were evaluated by proximate and ultimate analysis. High resolution-transmission electron microscopy (HR-TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier transforms infrared (FT-IR) spectroscopy, X-ray powder diffractometer (XRD), UV–visible (UV–vis), and fluorescence (FL) spectrophotometer were used to achieve physico-chemical parameters of carbon nanostructures, to better comprehend the development of carbon quantum dots and graphene nanosheets. HR-TEM analysis indicates that the dimensions of the synthesized CQDs from different carbon sources exist in the range of 3–6.5 nm. The approximate quantum yields (QY) of the synthesized carbon nanomaterials were found to be about 2–22%. The synthesized carbon based nanomaterials (i.e. CQDs and GNs) have been efficiently used in the photo-degradation of harmful 2-nitrophenols (2-NP) with the efficiency of 80.79% for CQDs and 82.53% for GNs, respectively. The present study provides a simple and environmentally-sound technique for large-scale fabrication of typical CQDs and GNs from abundantly available low-grade coal and other carbonaceous materials for photo-catalysis application

Oxidative chemical beneficiation of low-quality coals under low-energy ultrasonic and microwave irradiation: an environmental-friendly approach

The present environmentally-friendly coal processing technology discussed herewith focuses on the combined effect of ultrasonic and microwave energy in the extent of mineral matter (ash yield) removal from high-sulfur, low-quality coals for their clean utilization. The novelty of this study is that the technique is very efficient instead of using drastic chemicals with less treatment time, less amount of reagent in comparison to the conventional method, and has the potential to adopt in large-scale commercial production of cleaner coals. The quality of the cleaner coal products was examined by using chemical analysis and advanced analytical techniques (electron beam analysis). The combined irradiation process of ultrasonic and microwave energy is observed to be the most effective for the beneficiation of high-sulfur coal than the single process. The result showed a maximum of 51.28% and 66.34% ash (mineral matter) removal from the coal samples by microwave followed by an ultrasonic process. The X-ray photoelectron spectroscopy (XPS) analysis revealed that both inorganic and organic sulfur is present in these Cenozoic low-rank, high-sulfur Indian coals. The high resolution-transmission electron microscopy (HR-TEM) image analysis of the treated coal samples showed nearly agglomerated collections of nanomaterials; carbon spheres/flacks with an irregular shape; and the elements such as oxygen, iron, silicon, sulfur, and aluminum in the beneficiated coal samples. The major mineral phases, including quartz, kaolinite, and gypsum, are found to be removed during the beneficiation process. The thermal analysis (TGA-DTG) also showed the suitability of the beneficiated coals for the power plant application

COMPARATIVE REVIEW OF CROATIAN AND INDIAN AIR POLLUTION STUDIES WITH EMPHASIS ON POLLUTANTS DERIVED BY COAL COMBUSTION

Zdravlje ljudi, okoliš i klima pod velikim su utjecajem složenih interakcija onečišćujućih tvari u atmosferi. Gotovo sve ljudske aktivnosti uzrokuju ispuštanje onečišćujućih tvari u zrak. Njihovo razumijevanje i kvantifikacija prvi je korak prema kontroli i ublažavanju onečišćenja zraka. Opći cilj ovoga rada jest prikaz rezultata odabranih hrvatskih i indijskih znanstvenih radova koji se bave onečišćenjem zraka, posebice onih s naglaskom na sumpor i aerosole povezane s elektranama na ugljen. Dvije zemlje u osnovi se razlikuju s obzirom na njihovu veličinu, zemljopisna obilježja, povijest, gospodarstvo i industrijski potencijal. Međutim, obje zemlje imaju određene veze s pridobivanjem fosilnih goriva i njihovom uporabom u elektranama i industriji već desetljećima. Prikazani su različiti znanstveni pristupi u istraživanjima te državne politike u legislativi onečišćenja zraka.Human health, the environment, and climate are being profoundly aff ected by complex pollutant interactions in the atmosphere. Almost all human activities cause the emissions of air pollutants. Their understanding and quantifi cation is the fi rst step towards the control and mitigation of air pollution. The general aim of this paper is to summarise the fi ndings of selected Croatian and Indian papers addressing air pollution, particularly those focusing on sulphur and aerosols associated with coal-fi red power plants. The two countries are essentially diff erent regarding their size, geography, history, economy, industrial potential, to name but a few. However, they both have had certain relations to the fossil fuel extraction and its usage in power stations and industry for decades. Various research approaches are presented, together with a brief outline of national air pollution policies

Nanoparticles from construction wastes: A problem to health and the environment

The present study deals with the nano-mineralogy and geochemistry of ultrafine particles in construction waste from the Porto Alegre region in Southern Brazil. Uncontrolled construction waste dumps and poor management practices in formal disposal sites in the area may increase exposure risks to population. Whilst the physicochemical properties of construction wastes are well documented in the literature, the characteristics of nanoparticles in their formulations are not well known. Given that degradation of construction materials may unlock and enable further release of nano-particulates present, we focused on the <63 mm fraction to examine the geochemistry of inhalable nano-particulates that could cause adverse health impacts on local communities. A particular feature across the studied wastes are the numerous aerodynamically favourable, spherical-shaped nanoparticles of magnetite, rutile and anatase. The detected nanoparticles contained a number of elements including Al, As, Au, Ca, Cd, Co, Cr, Cu, Hg, Na, Fe, K, S, Sn, Si and. An enrichment in metals and metalloids such as As, Co, Cr, Cu, Hg, Fe, Sn or Ta in particles in the nano-scale range in relation to larger particles was observed. The presence of carbon nanotubes was also noted. The leaching tests showed that the construction wastes did not reach the limits for their disposal as hazardous waste according the European Directive. Whilst the majority of trace elements were highly immobile, the water extractability for oxyanionic-forming metalloids suggests possible migration to surface and groundwater bodies. This work seeks to bring awareness on the impacts of unsustainable construction waste management, and the relevance of improved regulations regarding their final disposal

Pollution from uncontrolled coal fires: Continuous gaseous emissions and nanoparticles from coal mines

In this investigation, the coal fires in different Colombian coal mines were studied using advanced electron beam and X-ray diffraction techniques. The results were compared with information from highresolution transmission electron microscopy (HR-TEM) equipped with a dispersive X-ray detector (EDS). Amorphous phases, salammoniac, anatase, muscovite, goethite, jarosite, calcite, gypsum, kaolinite, illite, and quartz are the dominant mineral matter constituents in almost all of the coal fires, with minute quantities of native sulfur, magnetite, siderite, pyrite, pickeringite, epsomite, hexahydrite, halotrichite being present in around half of the investigated coal fire samples. Other minerals that are present in some particular samples are chlorite, ankerite, and dolomite. Fe-sulfides were also detected particularly in the pyrite-bearing coal fires, possibly indicating oxidation of the Fe-sulfides occurring with coal fires. Exhaust discharge data indicate an overall trend of reducing carbon dioxide (CO2) and carbon monoxide (CO) releases (between 1.5 and 34%) from the coal fires. This is the first report on Colombian coal fires, which would be important for different perspectives of the research in the area

River dynamics and nanopaticles formation: A comprehensive study on the nanoparticle geochemistry of suspended sediments in the Magdalena River, Caribbean Industrial Area

The coastal zones on continental shelves are the main channels for the distribution of fluvial-sourced suspended sediments (SSs). In the current research, the monthly average amount of SS draining into the Caribbean Sea from the Magdalena River in northern Colombia was analyzed to detect nanoparticle (NPs) containing potential hazardous elements (PHEs). The ecological authorities of Colombia claimed that the climate change is the key reason behind land erosion and floods occurred in the last years; therefore, an elaborate understanding of NP dynamics between the Magdalena River body and streambed is an essential issue in SS research. In this work, the NP geochemistry of SS in the Magdalena River estuary was studied from the perspective of water quality controls on SS sorting. The morphologies and the structures of NPs (<100 nm) were examined by field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HR-TEM), and selected area electron diffraction (SAED)/micro-beam diffraction (MBD)/energy dispersive X-ray spectroscopy (EDS) techniques. The average size of NPs was found to be greater than 2 nm and Al, Ti, Fe oxides, and other hazardous elements were also detected in the SS. The obtained data confirmed that these typical categories of NPs caused the occurrence-dependent intensification of a conjugative transmission rate associated with the regulators. The advanced electron beam technique provided a clear insight into SS transportation; therefore, it could be used as an essential instrument for river supervision/dynamics

Feasibility studies of formation of carbon foam from high sulfur Meghalaya coal

Carbon foams have been produced from a high sulfur sub-bituminous Meghalaya (India) coal with good plasticity properties using a two-stage thermal process under different conditions of pressure and temperature. The first stage consists of a controlled carbonisation under pressure at 450°C, while the carbonisation product is baked at 1100°C in the second stage. The foams show macroporous texture. The mean pore size and the volume of pores have been determined. The increase in pressure reduces the pore size, while the pore volume increases with increasing temperature

Feasibility studies of formation of carbon foam from high sulfur Meghalaya coal

433-436Carbon foams have been produced from a high sulfur sub-bituminous Meghalaya (India) coal with good plasticity properties using a two-stage thermal process under different conditions of pressure and temperature. The first stage consists of a controlled carbonisation under pressure at 450°C, while the carbonisation product is baked at 1100°C in the second stage. The foams show macroporous texture. The mean pore size and the volume of pores have been determined. The increase in pressure reduces the pore size, while the pore volume increases with increasing temperature